1. Field of the Invention
This invention relates to a marking apparatus for use with transfer tape and more particularly to a multiple imprint marking apparatus having individually powered marker heads which are adjustably positioned to imprint a variety of packaging films.
2. Prior Art
Most present day marking equipment used to imprint packaging films or the like with current information, such as date coding or pricing, provide machines which utilizes a transfer tape in which pigmentation is transferred to an imprinting surface by means of pressure and/or heat. While such tape provides an excellent imprint, it has the disadvantage in that once an area of the tape has been used for imprint, the pigmentation is removed and this area may not be reused. Accordingly, after each imprint cycle the tape must be advanced to provide a fresh new area for each subsequent impression that is to be made.
Machines using this tape provide a marker head which is supported in a frame for reciprocative movement relative to an imprint surface whereby a printing block, equipped with raised indicia, strikes the tape to apply the imprint to the imprint surface, positioned immediately adjacent the transfer tape in synchronism with a stop and go movement of the imprint surface. The marker head, which often includes a heating block is attached to a carriage for reciprocative movement along a pair of guides supported on the frame. The carriage is usually moved by means of an actuator slide having a curved cam slot therein with operative engagement with a follower carried by the carriage. Thus, as the slide is moved back and forth by means of a fluid cylinder the cam slot and follower are effective to impart the imprint motion to the marker head. While these devices have been extremely successful, they are not readily adaptable to provide multiple impressions as is desirable when sheet packaging material is utilized providing a series of side-by-side packaging film areas. Heretofore a pair of independent marking devices have been utilized each of which are supported and operable independently of the other. This arrangement has not been entirely satisfactory because of excessive costs, space requirements and complex mounting and control arrangements needed.
Attempts have been made to produce simultaneous impressions on packing film with the use of a single unit providing a pair of marker heads carried on a common carriage and actuated by a single power means. These devices however, have proved difficult to adjust and to position the heads when working with varying width packaging films resulting in poor impressions and often faulty register of the imprint on the generally limited size imprint area frequently provided. Further, since the transfer tape must provide independent tracks for each marker head, it proved necessary to skew the entire marking apparatus relative to the path of travel of the packaging film, which further complicates the registering adjustment of the marker heads to "square" the indicia with the film. Slight misalignment or faulty adjustment will accordingly produce a defective impression which is exceedingly serious since these marking devices apply important last minute information such as pricing, dating or other coding to a packaged product.
Further, when more than two side-by-side film packaging areas are utilized with a roll of packaging film, proper adjustment and positioning of the marker heads to provide good register and uniform impression density is virtually unattainable.
It would therefore be a decided advance in the state of the art to provide a fully adjustable multiple head imprinting device utilizing a transfer tape to imprint various side-by-side packaging areas generally simultaneously along a length of a packaging film.